I installed User Role Editor. But I may not have needed it. After you've uninstalled the plugin(s), go to Roles for EACH ROLE under the Users Menu. Activate a role. Keep Administrator for last. Uncheck the many added capabilities belonging to Ai1c. Update the role. The item will disappear. Once all the roles other than administrator are updated, then check the Administrator role. See if those items are still there. If they are, then uncheck them in Administrator. Update the role. The errant capabilities should all be gone. If I'm not mistaken, they couldn't be deleted if they were assigned to at least one role. Once they were unassigned, they were able to be deleted.
I briefly checked the database to see if they're still there, but I would bet they're gone.
Do this for each of the deleted plugins that create role capabilities. Others that cause left-behind-in-the-database problems are CalPress-Events, The Events Calendar by Tribe, and S2Member (this is by no means a comprehensive list - I'm way too new to WordPress).
Then, in the interest of not having too many plugins, I deleted User Role Editor.